Other than the Init_$extension() function, the only reason
to have public symbols is for large C extensions that need
to span multiple .c files and we're not one of them.
This can help us notice real bugs in our code sooner.
Some of the unused variable warnings are pedantic from our usage
of -Wextra, but GCC >= 3 provides us with a handy attribute we
can use to mark variables unused. -Wextra is also a default
flag for 1.9.2dev, so we might as well get used to it.
There are still some corner-case calls which may cause
network activity and block the socket, but the majority
of reads/writes on the socket will release the GVL under
1.9 and be signal-safe under all versions of Ruby.
We'll also make a note of all functions calls that passed
visual inspection and add FIXME for a few more corner
cases we still need to fix.
mysql_real_connect() is a blocking function that issues
blocking-but-interruptible connect(), read(), and write() system
calls. So we'll allow other threads in the VM to run while
calling it since it can block indefinitely.
This introduces a rb_thread_blocking_region() wrapper for 1.8
which ensures any received signals can be handled gracefully
while inside blocking function calls.
This allows the caller to iterate over the Mysql2::Result instance as many times as they want, lazily pulling what rows are needed from the mysql C result.